Damper assembly

ABSTRACT

A damper assembly is provided in a rectangular frame with streamlined blades rotatable on parallel shafts. The shafts may be square in section and ride in square orifices extending through hubs of the extruded blades. Air, smoke or other gaseous leakage is immeasurably reduced between the ends of the blades and the frame by a unique composite seal disposed between the end of the blades and the damper frame.

Waited States Gaming et a1.

DAMPER ASSEMBLY Inventors: Lionel-P. Calming, New York City;

Frank J. Fromwilller, New City, both of N.Y.

Imperial Damper Co., Inc., Bronx, N.Y.

Filed: Oct. 14, 1971 Appl. No.: 189,085

Assignee:

us. ca. 98/110, 98/121 Int. Cl F24f 113/08 Field of Search 98/40 V, 40VM, 40 R, 98/41R, 110,121

References Cited UNITED STATES PATENTS 4/1963 Scharres 98/110 X Jan. 8,1974 3,123,098 3/1964 Bishop 98/110 X 3,180,246 4/1965 Johnson....98/110 3,547,152 12/1970 Hess 137/601 3,606,245 9/ 1971 Reichow 137/601Primary ExaminerMeyer Perlin Assistant ExaminerR. CaposselaAtt0rneyLilling & Siege] [5 7] ABSTRACT A damper assembly is provided ina rectangular frame with streamlined blades rotaable oii'pariila sh aitsi The shafts may be square in section and ride in square orificesextending through hubs of the extruded blades. Air, smoke or othergaseous leakage is immeasurably reduced between the ends of the bladesand the frame by a unique composite seal disposed between the end of theblades and the damper frame.

13 Claims, 18 Drawing Figures PATENTEDJAH 8 m4 3.783.768

INVENTORS. LIONEL P. CAMING FRANK J. FROMWILLER ATTORNEYS PATENTEDJAN 8I974 SHEET 2 BF 5 INVENTORS.

LIONEL P CAMiNG RY FRANK J. FROMWILLER A TTOR N 4 S PAIENTEUM 8 I9743783768 sun-:1 3 or 5 INVENTORS. LIONEL P CAMING FRANK J FROMWILLER 2ATTORN Y5 PATENTEDJAH 8 I974 SHEET IUF 5 FIG. 9

agvaakrss PATENTEDJAH 8 I974 SHEET 5 0F 5 INVENTORS. LIONEL R CAMING [yFRANK J. FROMWILLER ATTO ZNEYS DAMPER ASSEMBLY BACKGROUND OF THEINVENTION The present invention relates to improvements in the designand construction of flow control devices, generally known in the art asdampers or louvers.

In many instances, largely associated with the flow of gaseous fluids invarious temperature control systems, such as heating, ventilating andair-conditioning; it is required to regulate the flow of a fluid acrossan aperture or through a duct continuously from substantially completecessation of such flow to the maximum rate possible under the availablepressure differentials.

It is known in the art to supply a damper, or louver assembly in suchinstances with a number of parallel, planar blades pivoted near theiraerodynamic centers of pressure and provided with mechanisms to rotatethem around their respective pivots. These blades may cooperate informing a complete block to flow through them, or alternately, may bepositioned to expose their thickness, rather than their chord, to theflow and thus provide the least possible interference with it.

It is also known that the practical construction of such damperassemblies is attended by many difficulties, notably in securing thebest possible seal against leakage when closed, the least impedance toflow when open, and the provision of operating linkages or mechanismsrequiring the least possible actuating force and which providesextremely long life of operation substantially free of any malfunctions,such as binding of blades or need of job-site servicing.

For commercial success it is also necessary that the design chosen beadaptable to many differing conditions having wide temperature ranges,varied gases, pressures'and sizes, and that the operating mechanism bereadily arranged for both parallel blade rotation and counter-rotationof adjacent blades, such motions being preferred alternately in theseveral applications of such dampers.

SUMMARY Accordingly, it is therefore, the principle object of thepresent invention to provide a novel sealing device for reducing theleakage past the ends of the blades of a louver assembly by providing acomposite seal between the frame and the blades comprising a unique sealhaving an arcuate, outer, elastic member of metal or plastic and aresilient inner backing element secured thereto.

It is another object of the' invention to describe novel constructionsfor the individual louver blades, readily adapted to the provision ofmany different widths and lengths from prefabricated components.

It is yet another object of the invention to teach the use of a novelpivot-shaft, square in cross-section, for increasing the rigidity of thelouver blades and preventing the slippage of the latter in their shafts.

It is a further object of the invention to describe methods for joininga number of complete louver as-' ments and repair; thereby leading toassured commercial success.

These and other objects, features and advantages of the presentinvention will become more apparent from the detailed descriptionherewith considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of adamper of the invention shown in an open position;

FIG. la is an enlarged fragmentary view of the sideseal for the damperof the invention;

FIG. 2 is a side elevational view ofa damper assembly withcounter-rotating blades;

FIG. 3 illustrates the embodiment of FIG. 2 with all blades rotating inthe same sense;

FIG. 4 is a sectional view of the damper assembly il- Iustratingconstruction of tip-seals;

FIG. 5 is an exploded, perspective view of an actuat ing arm for adamper blade;

FIG. 6 is a detail exploded view of a connector link employed in theembodiment of FIG. 2;

FIG. 7 illustrates a portion of the frame of a multiple damper assembly;

FIGS. 8 and 9 are sectioned views of the jointed frame along the lines88 and 99 of FIG. 7;

FIG. 10 is a detailed sectional view-of the pivotbearing assembly;

FIG. 10a is an end view or sectional view of the bearing assembly alongthe lines of l0a-10a of FIG. 10;

FIG. 11 illustrates an alternate embodiment of the louver vane;

FIG. '12 shows a section of another embodiment of the louver or damperblade;

FIGS. 13 and 14 indicate the method of construction of built-up damperblades;

FIG. 15 is a sectional view of the side-seal assembly of FIG. la as maybe employed for sealing the top and or bottom rails; and

FIG. 16 is another sectional view indicating the manner of providing adust-seal cover for the actuating mechanism of the damper assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, thereis shown and illustrated a damper assembly with three streamlined blades5a, 5b and 5c. The blades are mounted on parallel pivot shafts,typically 6a, subdividing the aperture of a rectangular frame composedof siderails 1 and 2, bottom-- rail 4 and top-rail 3. The blades 5 arein the fully open position, with their chords perpendicular to the planeof the aperture and pose little resistance to the flow of a fluid therethrough. The shaft 6a is preferably square in section so as to provideinstant and positive (no slip) blade control and it extends beyondside-frame 1 to receive lever arm 7a, to be further described withreference to FIG. 5. The several lever-arms 7 are connected by push-rod8; a regulating mechanism suitably of a manual or mechanised design,acts on an extension of the push-rod 8 to open and close the blades 5 byrotating their pivot-shafts 6. These mechanisms have been omitted forclarity; their designs are well extablished in the art and form no partofthe present invention disclosure.

A small enlarged fragmentary sectional view of the siderail2 is shown inFIG. 1a. The unique seal 9 is formed of an outer flexible, spring-likemember 11 and an inner compressible, resilient backing member 10. Theinner member 10 may be of any suitable elastomeric material, such aspolyvinylchloride, a sponge-like material or a soft neoprene rubber. Theouter flexible member 11 may be of a thin, deformable metal, such ascopper, bronze, stainless steel, or even of a plastic material, such asteflon, nylon, etc. The inner element 10 is suitably affixed to theouter member as by an adhesive. The seal 9 is disposed in the gapbetween the end of blades and the side frame members 1 and 2 and is sodimensioned that it is slightly compressible at all points contactingthe blades, as the blades move from an open to a closed position. Theseal 9 prevents the flow or passage of gases past the gap between theframe and the blades thus providing the damper assembly with positivescaling properties. The inner member serves to keep any gas or air, etc.from leaking past the side seals 9 and they also prevent gas or airleakage around the shafts passing from the blades through the sides ofthe frame. Such member is also particularly effective, as will bedescribed hereinafter, about the area around the shaft bearings, whichheretofore have been areas where gas or air leakage has been extensiveand difficult to overcome.

The inner member 10 also insures and aids in providing proper rigidityto retain correct tension of the outer member or side seal against theends of the blades. Thus, the ends of the blades force the inner membersof the side seals against the side rail frames 1 and 2 and the inherentresiliency of the outer member maintains the side seal in a compressiblestate when the blades are in an open position. The outer member istherefor when not compressed by the blade ends in its originaluncompressed condition.

FIG. 5 is a more detailed illustration of the lever-arm 7 whose body ispierced or bored by a square hole 77 so dimensioned that a sliding fitis obtained upon the insertion of shaft 6 therein. Provision is made forsetscrews 75 to engage the shaft 6 once proper alignment has beenobtained. The elongated hub 70 of the leverarm 7 carries two pairs ofparallel extensions which, in turn, are pierced by circular openings71/72 and 73/74, respectively. A wrist-pin 83 fits through bushings 81and 82 inserted into bearing holes 71 and 72; the wristpin 83 being acylinder whose axis is aligned parallel to, and offset from, the axis ofthe orifice 77 and whose diameter carries a bore 88 to receive thepush-rod 8. The

push-rod 8 and the wrist-pin 83 may be locked together by a set-screw 84providedalong the axis of the latter. By this construction, the linearmotion of the push-rod 8 may be converted into rotational motion of thearmy depicted in FIG. 1, with the mechanism arranged to v rate driveswere to be connected to push-rods 8 and 108, means for synchronizingtheir motion would be necessary for reliable operation. This function isundertaken by connector 30, linking pivot pins passing through holes 73and/or holes 74 in adjacent leverarms, typically 7b and 7c.

The connector 30 is further illustrated in FIG. 6; it is comprised of apriamry element 35 and a secondary element 31. The primary element 35 isan elongated, flat member with tabs 35a and 35b forming a channel alongits major axis at one end, and a Z-shaped yoke-piece 38 forming a clevisat the other. The secondary element 31 is similar in shape to the member35, except for the tabs of the latter which are omitted, and is sodimensioned that its width is a snug fit between the tabs 35a and 35b.Both elements 31 and 35 carry elongated holes, 42 and 41 respectively insuch a manner that they may be locked together by bolt 36 being passedthrough these holes in succession and nut 37 tightened upon the bolt. Inthis manner relative axial motion between the two elements of theassembly 30 is prevented by the bolt 36 and rotation by the tabs 35. Thesecondary element 31 also carries on its outboard end a clevis formed bya Z- shaped element 32. Both clevises of the connector 30 are bored toreceive pins 33 and 39 respectively; these pins being also used to formrotatable joints in cooperation with bearing holes 73 and 74 in theextensions 78 and 79 of adjacent lever-arms 7.

When installed, as in FIG. 2 between lever-arms 7b and 7c, the connector30 provides a rigid, adjustable link for the transmission of rotarymotion between the shafts 6b and 60. If the lever-arms are arrangeddegrees out of phase relative to one another, such rotary motion will bein opposite sense of the two shaft's. Should one connector 30 proveinsufficiently rigid for the imposed loads, another, identical assemblyis readily mounted between projections 74 of the same leverarms.

The above construction permits a number of alternate arrangements forcounter-rotating assemblies; in particular it admits of the use of anunpowered pushrod 108 driven from the powered push-rod 8 of theembodiment of FIG. 2. It is also possible to provide only one push-rod,connected to alternate arms on the shafts 6, with each of theintervening blades being driven through a connector 30 from one of itsneighbors.

FIG. 3 is aside-view of another form of the damper assembly, with theblades rotating in the same sense to open and close upon the actuationof the push-rod 8. The arrow B indicates the direction which thepush-rod 8 is moved to open the blades, the motion being transmittedthrough lever-arms 7 to the shafts 6.

It should be noted that all actuating mechanisms in these embodimentshave their moving parts mounted in, and partially enclosed by, theside-rail 1, thereby avoiding the use of levers and pivots exposed tothe flow of fluids and to the attendant dangers of collecting dust andaccelerated corrosion which characterize 'many designs in the prior art.

FIG. 7 indicates the manner in which the unit damper assemblies of theinstant invention may be combined to form control elements for extremelylarge apertures exposed to fluid flow. Common side and top rails 102 and103. extend along perpendicular boundaries of the aperture and aresecurely 'joined'at their intersection by gusset 100. The fielddefined'by these members, cooperatively with elements 101 and 104,,notillustrated,

which are mirror images of their counterparts 102 and 103, is subdividedinto a number of rectangles of equal dimension defined by partitions 1a,4a, 2b, 4b, and so on. To provide a mechanically sound and rigid basefor damper blades and their operating mechanism, these are furtherjoined one to another by standardized connectors 50 and 51.

FIG. 8 indicates a typical side-frame joint, between elements 1a and 2b.These elements are identical extrusions, in aluminum for preference, andcarry along their axis a number of integral grooves and channels,notably grooves 21 for receiving sealing members of the damper assembly,similar grooves 23 and 24 on the outer faces of their U-shapedcross-section for receiving connectors 50 and 51, as required, andpartly open circular sockets 24 to serve as anchorages for selftappingbolts for securing elements joined at right angles to one-another. Theconnectors 50 and 51 are also extrusions, the former L-shaped andprovided with an integral dovetail key, fitting the grooves 23 and 24,along the outer surface of one leg, the other U-shaped.

Typically, grooves 22 in adjoining edges of members la and 2b have shortlengths of connector 50, 50a and 50b for example, inserted into them;the latter being aligned and drawn together by means of a fastener,suitably a rivet or a bolt 52 engaging a nut 53.

Grooves 23 also receive short length of connector, 50c and 50d in FIG.8, the gap, if any, between them being bridged by a length of connector51 which is fastened to both connectors 50c and 50d.

Top and bottom rails of adjacent dampers are joined in a similarfashion, as shown in FIG. 9, by inserting by imposing psi on a RobertShaw Pneumatic motor. A static pressure of 4 W.G. was then built updirectly upstream of the damper, and, at that pressure, the pressuredrop was monitored across a "/s knife edged orifice plate installed inthe system and the leakage was determined to be 4 CFM per square foot.

lengths of connector 50 into the integral dovetail grooves 23 anddrawing the latter together by means of an appropriate fastener.

As noted hereinbefore with the use of more conventional dampers, aconsiderable amount of fluid generally leaks past the pivot bearings ofthe blades. The suppression of such leakage is an important feature ofthe use of the seal 10 in the damper assembly of the present invention.A specific bearing assembly is illustrated in FIGS. 10 and 10a, theshaft 6 protruding through adapter-sleeve 49 and flanged bearing 47. Thesleeve 49 is provided with a square internal orifice closely fittingover the shaft 6 and a cylindrical outer surface which is a sliding fitin the'bearing 47, the flange 48 of which rests against the side rail 1.The bearing 47 has a cup-shaped cross-section, the base of which ispierced by a circular hole slightly larger'in diameter than the diagonaldimension of the shaft 6. If desired, keying means or locating lugs (notshown) may be employed in retaining the bearing 47 in place so that samewill not rotate along with the sleeve 49 and shaft 6. Of course, theside seals (elements 10 and 11) are suitably bored so as to receive theshafts therethrough; and such side seals also aid in serving to retainthe bearing assemblies in place, although same are pressfitted into theapertures provided in the side rails for the bearings 47.

In order to illustrate the effectiveness of the side seals In anothertest without the unique side seals, a 2 ft. X 1 ft. opposed bladedamper, Imperial Damper Co., Type Ill-0 of the same material as aboveand frame size, the other sides being of 2 X a X a inch size and thedamper was actuated with a Powers Regulator, Pneumatic motor, which shutthe damper at 18 psi. The duct was 5 X 2 X 1 feet with the damper in thecenter and a blower capable of 27,000 ft./min. was used to supply theair for this test. A hole was drilled into the piping that is connectedto the 5 ft. long duct in order to determine the static pressure using atube and manometer. A louver type damper was installed into the pipingin front of the manometer so that the static pressure is obtained. Thedamper was then closed using 18 psi of air and readings obtained at thefar end were Static Pressure 4 inches, velocity 8,000 ft./min. and AirFlow Leakage of 27 CFM per square feet.

Thus, leakage is significantly reduced when the novel side sealsdisclosed herein are employed in a conventional damper construction.

FIG. 11 illustrates a vane with a thickened hubportion 101 centrallylocated in its substantially flat face, the hub 101 being provided witha square orifice 106 for engaging a shaft 6 of the damper assembly. Atthe outboard extremities of the vane 105 small, planar projections 104are provided, extending in opposing directions at right angles from themajor surface of the vane and carrying, in their acute corners, dovetailgrooves 103 which serve to anchor suitable sealing strips 102. The seals102 of two adjacent vanes in a louver cooperate with the projections 104of the neighboring vane to form a tight seal upon rotation of the vanesinto their closed position, thereby preventing the flow of fluid pastthe tips of adjacent louver elements.

A streamlined damper-blade 205 is illustrated in FIG. 12. The blade 205has two symmetrical curvillinear surfaces with maximum separation at themidsection of its chord, tapering gently towards sharp edges at eitherextremity of the chord. With respect to the manner of construction, theblade 205 is preferably a hollow extrusion with a square orifice 206being formed at its midsection by the side-walls and interconnectingpartitions 201a and 201b. The orifice 206 accommodates the shaft 6 whichmodulates the angular position of the blade 205.

Another design of the damper-blade, for use in the preferred embodimentof the instant invention, is illustrated in FIG. 13. A central boss 306is formed by a square extrusion and is provided with deformable, toothedextensions 307. The internal orifice formed by the walls of the boss 306fits over the shaft 6 and forms the hub of a blade completed by theaddition of members 304 and 305. The member 305 is a hollow extrusionwhose cross-section approximates to one-half of the streamlined blade205; its base 301a being provided with rigid, toothed extensions 309which engage the mating projections 307 of the hub 306 in a snap-jointber 304 is also a hollow extrusion tapering from a thickness equal tothat of the hub 306 to a point and continuing therefrom as a flat platecarrying a tip-seal 302 analogous to the similar component 102 of thevane 101 previously described.

Yet another method of constructing a composite blade is illustrated inFIG. 14 which shows a partial blade 405, similar in cross-section to thestreamlined blade 205 and incorporating a central orifice 406 forreceiving the shaft 6. The orifice 406 is bounded by the side walls ofthe partial-blade 405 and webs 401a and 401b; the side-walls beingterminated at the web 401b from which extend deformable, toothedprojections 407 which are dimensioned to fit into mating projections 309of the member 305 to form a snap-joint 403.

All of the above described components may be thought of as havingconsiderable lengths of constant section and may be cut into arbitrarylength blades, as required. The embodiments of FIG. 13 and 14 may befurther utilized in applications requiring blades of differing widths bychoosing appropriately dimensioned elements 304 and/or 305 inconjunction with a hub 306 or partial-blade 405. In this manner, bladesof either the vane or streamline type may be built up in a wide varietyof widths and lengths from a small number of stock extrusions, resultingin considerable economy of manufacture and assembly.

FIG. 4 shows a damper assembly in section with upper and lowerframe-rails 3 and 4 and built-up blades composed of partial blades 405and elements 305 mounted on shaft 6. The tips of the blades nearest theframe 3 and 4 are sealed, in the closed position, by sealing strips 24inserted into dovetail grooves 2. The seals 24 are manufactured from anelastomeric material, have an elongated cross-section and are mounted,along the inner surfaces of frames 3 and 4, by integral tongues fittinginto the aforementioned grooves 21. To minimize leakage past the tips ofthe blades, when closed, dovetail grooves 25 are provided in an outersurface of each of the blades, slightly offset from the blade-tips andsealing beads 26 of an elastomeric material anchored in them.

An alternate method of sealing the gap between the toprail 3 and theblade 5 is shown in FIG. 15, utilizing the sealing strip and shield 11in the same manner as the side-seal described with reference to FIGS. 1and 1a.

A vertical section through a segment of a damper assembly is shown inFIG. 16; a side-rail ll of U-section with unequal lengths sides 1 la and1 1b carries a typical blade 5 and its shaft 6 on which the actuatinghardware is mounted. The side walls 111a and lllb terminate in integralbeads 113 whichserve as receivers for a dustcover 112 constructed fromlight sheetmetal or plastic and whose function is to protect the damperoperating linkage from accidental damage during storage, transport andinstallation, and to keep out dust and other foreign matter.

The above disclosure described many applications and embodiments of thecomposite seal, square shaft, built-up blades and other features of theinstant invention. Arrangements, materials of construction other thanthose described are possible and may be substituted without altering thebasic principles of constructions disclosed herein.

What is claimed is:

1. A damper assembly for the control of the flow of fluids through arectangular aperture, comprising;

a frame with a first pair of sides joined, in parallel spacedrelationship, to a second pair of sides, similarly spaced;

pivot means, including at lease one shaft,

bearing means, for pivotally locating said shaft in said frame parallelto said second pair of sides, with a portion of said shaft protrudingbeyond at least one of said first pair of sides;

linkage means engaging said shaft on said portion protruding beyond saidfirst pair of sides;

louver means, including vanes or blades having hubs containing orificemeans defining a square orifice in a vane for keying said vane to saidshaft and said vane extending substantially between said first pair ofsides;

side-seal means having a thin, outer flexible member and an innerresilient member of an elasto-meric material secured to the innersurface of said outer flexible member; said side seals being pierced forpassage of said shafts therethrough;

said hub of said blade forming substantially a onehalf portion of saidvane and the other'portion of said vane is secured to said one-halfportion adjacent said hub by locking means which interlock said portionstogether in a substantially immovable position; and

drive means connected to said linkage means for rotating said vane onsaid shaft into the plane of said frame, thereby resulting in cessationof flow of fluids through said aperture; and alternately for rotatingsaid vane from the plane of said frame and thereby, permitting the flowof fluids through said aperture.

2. The damper assembly according to claim 1, wherein said vanes aredefined by convex arcuate surfaces symmetrical about chords thereofencompassing said hubs.

3. The damper assembly according to claim 1, wherein said innerresilient member is of an elastomeric material and said outer member isof flexible metallic material.

4. The damper assembly according to claim 1, wherein said outer memberis of a thin flexible plastic material and said inner resilient memberis of an elastomeric material.

5. The damper assembly according to claim 1, wherein said linkage meansinclude lever-arms with a central body portion having an orifice toslideably engage said shaft and provided with at least one pair ofextensions spaced along axes of said shaft and rigidly affixed tosaidcentral portion, each of said pairs of extensions lying in a planeincluding axis of said orifice.

6. The damper assembly according to claim 1, wherein a plurality ofshafts are employed and all of said shafts are square in section, andsaid louver means are keyed to said shafts by square orifices piercinghubs in midsection of said vanes.

7. The damper assembly according to claim 1, wherein said locking meanscomprises mating resilient extensions extending outwardly from saidone-half portion adjacent said hub and from said other portion of saidvane and said extensions having cooperative shoulders which grip eachother and thereby interlock said portion as a unitary one-pieceassembly.

8. The damper assembly according to claim 1, including blade edgesealing means between abutting surfaces of said blades for insuring aseal between leading edges of adjacent blades when said damper is in aclosed position.

9. The damper assembly according to claim 8, wherein said blade edgesealing means comprise elongated elastomeric bodies substantiallyrectangular in section, one edge thereof being keyed to inner surfacesof said second pair of sides.

10. The damper assembly according to claim 1, wherein said hub forms acentral element and said vane is secured to said central element bylocking means which interlock said elements together in a substantiallyimmovable position.

11. The damper assembly according to claim 10, wherein said lockingmeans comprises mating resilient and cooperative dovetail keys.

1. A damper assembly for the control of the flow of fluids through arectangular aperture, comprising; a frame with a first pair of sidesjoined, in parallel spaced relationship, to a second pair of sides,similarly spaced; pivot means, including at lease one shaft, bearingmeans, for pivotally locating said shaft in said frame parallel to saidsecond pair of sides, with a portion of said shaft protruding beyond atleast one of said first pair of sides; linkage means engaging said shafton said portion protruding beyond said first pair of sides; louvermeans, including vanes or blades having hubs containing orifice meansdefining a square orifice in a vane for keying said vane to said shaftand said vane extending substantially between said first pair of sides;side-seal means having a thin, outer flexible member and an innerresilient member of an elasto-meric material secured to the innersurface of said outer flexible member; said side seals being pierced forpassage of said shafts therethrough; said hub of said blade formingsubstantially a one-half portion of said vane and the other portion ofsaid vane is secured to said one-half portion adjacent said hub bylocking means which interlock said portions together in a substantiallyimmovable position; and drive means connected to said linkage means forrotating said vane on said shaft into the plane of said frame, therebyresulting in cessation of flow of fluids through said aperture; andalternately for rotating said vane from the plane of said frame andthereby, permitting the flow of fluids through said aperture.
 2. Thedamper assembly according to claim 1, wherein said vanes are defined byconvex arcuate surfaces symmetrical about chords thereof encompassingsaid hubs.
 3. The damper assembly according to claim 1, wherein saidinner resilient member is of an elastomeric material and said outermember is of flexible metallic material.
 4. The damper assemblyaccording to claim 1, wherein said outer member is of a thin flexibleplastic material and said inner resilient member is of an elastomericmaterial.
 5. The damper assembly according to claim 1, wherein saidlinkage means include lever-arms with a central body portion having anorifice to slideably engage said shaft and provided with at least onepair of extensions spaced along axes of said shaft and rigidly affixedto said central portion, each of said pairs of extensions lying in aplane including axis of said orifice.
 6. The damper assembly accordingto claim 1, wherein a plurality of shafts are employed and all of saidshafts are square in section, and said louver means are keyed to saidshafts by square orifices piErcing hubs in midsection of said vanes. 7.The damper assembly according to claim 1, wherein said locking meanscomprises mating resilient extensions extending outwardly from saidone-half portion adjacent said hub and from said other portion of saidvane and said extensions having cooperative shoulders which grip eachother and thereby interlock said portion as a unitary one-pieceassembly.
 8. The damper assembly according to claim 1, including bladeedge sealing means between abutting surfaces of said blades for insuringa seal between leading edges of adjacent blades when said damper is in aclosed position.
 9. The damper assembly according to claim 8, whereinsaid blade edge sealing means comprise elongated elastomeric bodiessubstantially rectangular in section, one edge thereof being keyed toinner surfaces of said second pair of sides.
 10. The damper assemblyaccording to claim 1, wherein said hub forms a central element and saidvane is secured to said central element by locking means which interlocksaid elements together in a substantially immovable position.
 11. Thedamper assembly according to claim 10, wherein said locking meanscomprises mating resilient extensions, extending outwardly from said huband said vanes and said extensions having cooperative shoulders whichgrip each other and thereby interlock said elements as a unitaryone-piece vane.
 12. The damper assembly according to claim 1, whereinsaid first and second pair of sides of said frame are provided withmeans for cooperating with associated means provided on connectors whichserve to stack a plurality of damper assemblies adjacent any side ofsaid frame.
 13. The damper assembly according to claim 12, wherein saidmeans comprises mating dove-tail grooves and cooperative dovetail keys.